DESCRIPTION: Congenital and infantile onset binocular imbalance affect the visual maturation of 3-4% of U.S. infants. These conditions have the potential to cause both amblyopia and abnormalities in binocular vision. Even after treatment which is successful in restoring clear media, good alignment, and normal acuity, less than 1% of patients achieve normal stereoacuity. During the previous grant period, early treatment for infantile esotropia and congenital unilateral cataract were shown to significantly improve stereoacuity and alignment. Proposed studies will build on these findings by evaluating whether further improvements in stereoacuity can be achieved when surgical alignment is accomplished at the onset of the critical period for stereopsis, whether severity of impairment of stereopsis is influenced more strongly by onset of misalignment or by duration of misalignment, weather better stereoacuity outcomes are associated with better long term alignment, and whether progressive occlusion therapy for deprivation amblyopia improves stereoacuity outcomes. The PI recent work with nasal-temporal asymmetries in the VEP motion response suggest a closer link to suppression than to stereopsis. Proposed studies will evaluate this hypothesis in infants and children with infantile or late onset esotropia or incomitant strabismus. In order to determine whether these sensory anomalies co-develop, VEP motion asymmetry, suppression, and stereopsis will also be evaluated in a group of infants at high risk for strabismus. The PI will also explore whether vertical motion asymmetries co-develop with or are predictive of dissociated vertical deviations. Using a newly developed hyperacuity protocol, she will evaluate the development of positional acuity deficits in amblyopic infants, examine their relationship with resolution deficits, and determine whether positional acuity provides a useful approach to monitor/predict the success of occlusion therapy. During the past grant period, she developed three tests of binocular sensory and motor function, the Infant Random Dot Stereocards, the Preschool Randot Stereoacuity test, and the video Hirschberg system. In the upcoming grant period, she will evaluate the accuracy, reliability, and validity of these tests. The video Hirschberg system will also be used to study the co-development of eye alignment and stereopsis in normal infants and the development of abnormal fixation patterns in pediatric patients. On the basic science side, these studies will help to define the necessary and sufficient conditions for the development of stereopsis. On the clinical side, better stereoacuity outcomes should provide more stable eye alignment and better quality of life.